JPS5918644B2 - Tractor tensile force detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tractor of the type equipped with a power-controlled implement pitch linkage, and more particularly:
The present invention relates to an improved tensile force sensing unit and linkage control device.

Tractors, particularly agricultural tractors, commonly utilize a liftable, power-driven, three-point pitch linkage to connect the tractor to implements. Typically, pull force sensing means are used to directly or indirectly measure the pull load between the implement and the tractor and actuated through the linkage control system to raise and lower the linkage and implement to provide a substantially constant preset pull. Maintain load. One way to automatically control a linkage is to measure the force acting on some part of the linkage and use changes in this force to control the vertical position of the linkage, thereby keeping the force relatively constant. It is to do so.

This type of control is commonly referred to as tension control. Various measurement means have been used, including connecting the upper or lower link to the tractor via a resilient member. This change in deflection of the elastic member can then be used as a control input. When a linkage member, such as a lower tension link, is connected to the implement at a point spaced from the lift point of the link, a reaction force having a vertical force and a horizontal force acts on the pivot point of the linkage.

Vertical forces are primarily due to equipment weight and soil suction forces, and horizontal forces are primarily due to horizontal tensile forces. Since the change in tensile force is a useful indicator for controlling the vertical position of the linkage to maintain a substantially constant tensile load, it is possible to eliminate the effects of vertical forces on the load sensing device. desirable. Linkage loads can be measured by measuring the bending displacement of a transverse shaft to which a rigid member is attached. This device was manufactured in 1977.
Patent application No. 116270, filed on November 21, 1983
No. In this device changes in vertical and horizontal forces are measured and amplified. An object of the present invention is to provide a tensile force sensing device which has the advantages of high force and precise sensitivity in the device of the above patent application and which eliminates the effects of undesired normal forces on the sensing device. . Other objects and advantages will become readily apparent from the following description and accompanying drawings.

Referring now to the drawings, FIG. 1 shows a tractor 1 connected to implement 3 by means of a pitch.

The pitch comprises a pair of lower links 5 (only one shown) and an upper link 7. Links 5 and 7 together form a normal three-point pitch. The lower link is connected to the lift arm 11 or raised by the lift link 9,
The lift arm 11 is fixed to the horizontal shaft 16.
The lift arm 11 is raised by a piston 14 operating within a hydraulic cylinder 13. Referring to FIGS. 2 and 3, the lower link 5 is supported on both ends of the shaft 17;
The shaft 17 is connected to the Fulcrum (Fu) inside the housing 15.
lcrum) supports or bearings 19.

The shaft 17 has a cylindrical part 17a1 in the horizontal plane and an intermediate part 17b which has a smaller diameter in the vertical plane.
1 and a reduced end portion 21 receiving a pole joint 23 on the lower link 5. The tractor has on each side a fork-shaped support member 25, in which the lower end of the piston rod 14a is arranged. piston rod 1
4a is pivotally connected to a short stubshaft 26. The reduced end portion 21 of the shaft 17 is loosely received within a recess 18 at the end of the short stub shaft 26. The reduced end portion is free to move within limits. A pair of plates 20 are carried on shaft 17 and attached to housing 15 by bolts 22.

These plates may be splined or flat 21a.
is non-rotatably attached to the shaft 17. This prevents the shaft 17 from rotating. The bolt passes through a slot 24 in the plate, which allows the shaft to move back and forth due to tension. As seen in FIGS. 2 and 3, the reduced portion 21 has a short stub shaft 2.
It can move freely within a limited range within a recess 18 at the end of the 6. Upon maximum bending of the shaft 17 in either direction, the reduced end portion 21 engages the side of the hole in the short stub shaft 26 and acts as a stop to limit further bending of the shaft 17. Elongated member 27 is secured to right end portion 17a of shaft 17 by clamp 28 (FIG. 2).

Bolt 29 serves to tighten the clamp onto the shaft. The other end of the elongated member 27 carries a roller 31 which engages a cam or cam member 33 rotatably carried on the left end portion of the shaft 17. As seen in FIG. 5, this cam or cam member has a cam surface 35 that engages the roller 31 so that the cam member 33 rotates about an axis coincident with the axis of the shaft. Cam member 33 is pivotally connected at its outer end to the lower end of link rod 37, which transmits the movement of cam member 33 to control mechanism C. A spring 39 acts between a stationary part on the tractor and the link rod 37 to force the link rod downwardly so that the cam member 33 abuts the roller 31. As seen in FIG. 5, there is an elongated arm 40 on the shaft 17.
is installed.

This arm has a slot 42 into which the roller 31 on the end of the elongate member 27 projects. This slot allows fore and aft movement of the rollers and elongated member 27 relative to the cylindrical shaft 17, but prevents relative vertical movement therebetween. Rotation of elongate member 27 and elongate arm 40 about the shaft axis is prevented by a pin 44 extending from a hole in housing 15 into a second horizontal slot 46 formed in arm 40. This slot allows horizontal movement of shaft 17 relative to housing 15, but prevents vertical and rotational movement of elongate member 27 and shaft 17 relative to the housing. The motion control means consists of arm 40, slot 46 and pin 44. The control device C does not form part of the invention in its details and may be of any suitable form comprising hydraulic valve means by which the hydraulic cylinder 13 and the piston 14 are connected. is activated and raises or lowers the link in response to changes in the load or force on the link.

When the tractor is pulling the implement, there is a tension or pulling force in the lower link 5.

This force acts horizontally on the reduced end 21 of the shaft 17,
Bend the shaft 17 as shown in the diagram of FIG. Figure 6 shows the shaft 17 in an unstressed or unloaded state.
shows. As shaft 17 bends, the clamping end of elongate member 27 remains parallel to the shaft at the clamping point. The other end of elongate member 27 is free to move horizontally within slot 42 so that elongate member 27 remains straight. Thus, the movement of the free end of the elongated flat member 27 relative to the shaft 17 is a function of the angle of excursion or inclination of the curve of the curved shaft. The effect of the vertical component of the force acting through the lower link 5 is shown schematically in FIG. Elongated arm 40 attached to shaft 17
restrains the rollers 31 on the elongate member 27, thereby bending the elongate member 27 into the same shape as the shaft 1T. Thus, there is no relative movement between the shaft 17 and the elongated member 27 and the vertical component of the force is therefore applied to the sensing member 33.
, 31, the sensing member operates only in response to changes in horizontal force as shown in FIG. When the loading effect of the weight of the implement supported on the tractor linkage is greater than the loading effect of the tensile force between the implement and the tractor, a compressive force acts on the lower link 5 and the cylindrical shaft 1
7 is bent in the opposite direction as shown.

The end of the elongated member 27 moves within the slot 42 to a point closer to the shaft than when the shaft is in its unstressed state. Figure 5 shows the unloaded position of the cam member 33 as a solid line and the maximum horizontal position as a dotted line. Cam member 3 under load
3 shows the extreme position. The dashed line 32 indicates the position of maximum tension when equal loads are applied to both ends of the shaft. The large and small dimensions of the intermediate portion 17b mutually extend across the length of the shaft.

In the illustrated embodiment, the major dimensions are cylindrical 17d and 1
7c, and the minor dimension is the dimension between flat sides 17f and 17g. Thus, the shaft is more sensitive to horizontal loads and the bending stresses generated by horizontal loads are lower than would be the case with a shaft having a uniform diameter equal to the large dimensions. Elongate member 27 has transverse major and minor dimensions, and in this embodiment, the major dimension of elongate member 27 is perpendicular to the minor dimension of the shaft.

In the large dimension, member 27 is relatively rigid, so roller 31 moves with the shaft parallel to this large dimension and measures the deflection of the shaft. In small dimensions, member 27 is flexible and easily bends with the shaft. Thus, member 27 flexes with movement of the shaft parallel to its minor dimension, and roller 31 does not move or become overstressed. The embodiment described above is only an example of one method of measuring the inclination or angle of the shaft 17 in the horizontal plane. Other means of detecting angular changes may also be utilized and are considered to be within the scope of this invention. Furthermore, this invention
It can also be applied to tractors when measuring the force in the upper link to control the linkage and maintain any predetermined tensile load. Such modifications are considered to be within the scope of this invention, which is limited only by the scope of the claims.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a tractor, pitch, and implement combination to which the present invention can be applied. FIG. 2 is a sectional view taken along a vertical plane, showing the connection of the tensile force detecting member and the tensile force detecting unit to the mounting body thereof. FIG. 3 is a sectional view taken along a horizontal plane, showing the tensile force detection unit and its mounting body. FIG. 4 is an enlarged sectional view taken along line 4-4 in FIG. FIG. 5 is an enlarged sectional view taken along line 5-5 in FIG. FIG. 6 is a diagram of the tensile force sensing unit in a no-load state. FIG. 7 is a diagram of the tensile force sensing unit showing horizontal deflection. FIG. 8 is a diagram of the tensile force sensing unit showing vertical deflection. 1... Tractor, 3... Tool, 5... Lower link, 7... Upper link, 9... Lift link, 11. ...Lift arm, 13...
・Hydraulic cylinder, 14... Piston, 15.
...housing, 16...horizontal shaft,
17... Shaft, 17a... Cylindrical part, 17b... Middle part, 21...
Reduced end portion, 24...Slot, 26...
... Stub shaft, 27 ... Elongated member, 3
1...Roller, 33...Cam, 37
... Link rod, C ... Control mechanism,
40...Elongated arm, 44...Pin, 46...Slot.

Claims (1)

[Claims] 1 an elongated horizontally extending shaft mounted on two spaced supports; and a tensioning mechanism connected to the shaft at two points spaced apart from the two supports, the tensioning mechanism acting on the tensioning mechanism; and a sensing mechanism for measuring relative movement of the shaft at a second end of an elongate member attached to the shaft at a first end. In the tractor pulling force detection device, the shaft of the detection device has a diameter in a horizontal plane smaller than a diameter in a vertical plane so as to be easily bent in the horizontal direction, and the detection mechanism measures deflection of the shaft in the horizontal plane. A tractor pulling force detection device characterized by: